High-tension installation



Patented NOV. 13, 1928. J y i Y i' .n 1 l y i g N* UNITED]STATVES ilailEISJT'joFFics.4

ARTHUR O.y AUSTIN, OF BABBERTON, OHIO, ASSIGNOR, -BY MESNE ASSIGNMENTS, y'IO lTHE OHIO BRASS COMPANY, MANSFIELD, OHIO, A CORPORATION F NEW JERSEY. ,1 L

- y HIGH-TENSION INSTALLATION.

Original applieationled October 20,1921, Serial No.:508,933. Divided and this application filed May 4,

` f 1925; SerialNo. 27,691..

'llliisinvention relates to installations for Spreading or splitting'the conductor into high electrical potentials, suchas high tenseveral parts so as to increase the eilective ysion transmission lines, wireless apparatus, ydiameter would be of material benefit, but and other` constructions, and has for its obthis is open to serious mechanical objections s ject the yprovision of mechanism of the class when carried out throughout the line or in 55 named which shall beofimproved oonstructhe, vicinity of the tower. y

tion and operation and which shall reduce the The insulators or portion of insulators ,tendencyl todischarge `of Y various charnextv the transmission lines carry `hi her rvacters from the highl chargedconductors electrostatic stress than those farther rom 1o through the control o the electrostatic iux the line duetowhat may betermedk the leakoo in the' medium surrounding suohconductors. age of electrostatic liux to ground from dift The invention is exemplied inthe eomyferent members in the series. The use of bination andy arrangement oi parts shown a very large conductor in the vicinity of the v intheaccompanying drawings and described insulator tends to prevent or kmake up for xr, in the following specilication, and it is more thislossoi electrostatic flux, thereby greato 4particularly pointed out in the appended vlv yimproving the stress distribution or gra- Claims `dient for the insulating member or members.

, This is a division of application, Serial No. The gradient or. stress. distribution in the 508,933, filed October20, 1921,' Patent Numseries may be improvedy by horns or iuX 2o ber 1,664,100, issuedMay 27,1928.. f controls, as shownfin my previous Patent To In thedrawings f f. y I Number 1,552,664,issued September 8,1925, v Fig. 1 is an elevation of an installation emor by a `large ring or shield. Where a ring bodying one form ofthe ,present invention; or shield is used to control the flux this ring Fig.. 2 is a View similar to Fig. '1 of a or shielclmay lower the iashover owing to Slightly mkodedlconstuction.; its yprojecting into a `strong field on the 75 Fig. 3 is a sectionl online 3-3 of Fig. 2; tower side so thaty it may more than oiiset Fig. 4 is a sectionon line 4-4'of Fig. 2;' the advantage of an improved gradient in and. 'y t. the insulator. f 4

f Fig. 5 is a View similar to Fig. 1 of another An .eight or ten sectionv insulatory of good form of the invention. l' t. z design will usually withstand a higher volt- Iny high tension insulators for transmission age than that which wllstart ank arc from and radio work as customarily used, a siX th@ CODdUCtOr-to the tower., a distance 0f y or eight section suspensioninsulator will orfrom live to ten feet, `depending upon elecl dinarily withstand al greater` voltage at al` trical conditions, although the length ot' the high frequency. without danger of arcing insulator may be only half this value. From than will the conductoron 'which the voltage this it will be seen thatusing a long string is impressed, unless the yconductor iso'f abo1" insulators may be. of little benelitvin pro- .normally large size. .It is, ofcourse, not `vidin'g a larger. factor of safety, as van arc veconomical to use a conductor which is so may start from theconductor to the tower. y

40 large that the first cost and interest on the This inventionis designedv to prevent this 90 investment will be excessive,"-,thereforey abarcing from conductor to tower by raising normally large conductors are not'kfeasible. the voltage to which arcing or pluming will `Even if there were suilicientpower ,to` waroccurand at the'same time reduce the danger f rant a very large conductor'for transmitting of aroing of the insulatory string by improvpower at a high voltage, the line'reactance ing the distribution of'stress in'same. 95 dueto the large current necessary for ecolr Owing Vto the rcomparatively small diamn omy'would be too -greatto permit ofk a size eter ofthe conductor and the comparativelyk sufficiently large to prevent arcing. of the4 .short distance to the tower, there is avery i conductor inthe .vicinity of the supporting strongfield about the conductor `in the vicinf towerwhere the electrostatic field isl-strong. ity of the tower so that by increasing the eff 10o fective diameter of the conductor by means of a properly formed shield or screen running along or adjacent to the conductor, the stress in the air is lowered and the corona point or Voltage necessary to start a plume or arc may be greatly raised and the danger of pluming` or arcing to ground under high frequency disturbances may be greatly reduced or eliminated.

'lhere are two classes of discharge into the air from insulators or high voltage conduc-v tors. One class atiects the performance of transmission lines very seriously due to the arcingl to ground at voltages much lower than would be indicatedby the voltage which can be carried at normal frequency. lrlhere a discharge from a conductor into the airis in the nature of a small streamer, the resistance of the streamer will be greatly reduced by increasing the current in the same. As this current may be regarded as a charging current the air acting as a dielectric in a condenser and a streamer as one of the conducting` plates, it will be seen that by increasing the frequency the current in the streamer will be increased accord ingly. Since, however, increasing the current in the streamer greatly reduces its resistance, the voltage drop along` the streamer will be less, consequently the high stress of the conductor will be carried out further from the conductor. This will cause a further break-down of the air, permitting` an increase in the electrostatic capacity of the condenser which affects the current and resistance of the streamer acting as one of the electrodes Tof 4the condenser. This further increase in current again reduces the resistance so that an accumulated effect is produced which is very-serious'wh'en a high frequency is impressed upon the line or insulator. This may be better understood when we consider that doubling,- the current in the streamer may cut its resistance in half.

From this it will be seen that while the resistance in a streamermight be excessively high at a normal frequency `of twenty-tive or sixty cycles, the same length of streamer would have almost a negligible resistance if the frequency isincreascd several thousand tfmes, which might easily occur on the transmission line. This increase in frequency over the normal frequency may come from a number of different causes, such as lightning and arcing teround, the effect of corona on the line in producing` a harmonie, the harmonics produced by connected apparatus, or other causes. A discharge then whichwill cascade because of the accumulative effect of current, either due to the reaching,r of a sutliciently hie'h voltage, or partially due to the increased current from an increased frequency, or a combination of both, may cause serious arcin;r or at least arcingto @ground atvoltages much lower than would otherwise be the case.

A small diameter of conductor, as was pointed out, permits a highly concentrated held which tends to produce streamers at comparatively low voltages. These streamer-s may exist at or even below the normal transmitting' frequency. lVhile there may be no trouble from the same other than the loss of power at normal frequency, an increase in frequency, particularly when attended by an increase in voltage, may permit ofthe growth of a streamer resulting in an arc to ground, as previously explained. lVhere the lsize of the conductor is increased the concentration of the field is reduced, and even though a. streamer starts, the accuniulative ell'ect will ybe so great and a much higher voltage and frequencyy may be im'iressed without producing' a plume or arc which will go to ground under disturbance, permitting the energy ofthe line to follow. Y

ln Fig. l is shown a suspension string of insulators l supporting,r a conductor 2 by means of a saddle 3. 'lhe effective diameter of the conductor in the vicinity of the insulator and tower is increased by a metallic cage 4 supported by a bar 5 secured to the saddle 3 at G and connecting with the cond uctor 2 at 7. The cage d may be made of wire or other suitable material wound in the form of a helix and extends for some dista ce alone' the conductor 2 away from the insulator l. The cages l are made in duplicate extending' in both directions from the insulator without causing the ends of the cages to interfere with one another. Suspended from the bar 5 and the conductor 2 at spaced intervals is a series of flux control members 9 which consists of metallic clamps secured to the conductor' 2 and the support 5 and entendina' downwardly therefrom, the lower ends of thedownwardly extending portions beine` covered l oy insulators l() to provide insulated flux distributors. In this figure the cage t is shown as surrounding the conductor, but in some cases it may be advisable to place the Vcage adjacent to the conductor or to one side, or the conductor Vmay be user to form part of the canje itselt. It will be readilv seen that this ca je greatly increases the e'lfective diameter' of the conductor so that a much higher voltage must be impressed to cause `a ni'licient concentration ofistress in the air to start a streamer than in the case of a relatively small diameter' of a bar conductor. The suspension string 'of insulators, being made up of a series of condensers, one end of which is connected to the conductor, sets up an electrostatic field. This electrostaticfield produced by the insulator` pproximatingif the Voltage of the conductor improves the air `gradient in its vicinity and will. tend to prevent streamers starting; in the immediate vicinity of the insulator.

.As the potential of the insulator approximates that in a streamer tending to start any arc,"there kwillbea tendency tocause repul- Sion due tothe well-known electrostaticy law of repulsion of like charges. This repulsion will be increased for a streamer starting from the conductor as the potential in the insulator string` approximates vthat of the, conductor. As previously explained, the conductor cage 4 being of much larger diameter than the conductorQ exerts a much greater eii'ect on the electrostatic'distribution'ofstress in the spring, the larger 'diameter tending to carry the conductor potentialhiwher up in the string, thereby tending to reduce the current in a streamer starting nearvr the insulator. Furthermore, if a streamer is startedthe ten: dency to carry tliefconductor. potential higher up in the string will lproduce greater electrostatic repulsion for the varc oil streamer rtending. to keep, saine` awayfroin the insulator. This latter is `importa-int,orif the energy yin the arc. following the discharge ,to ,ground takes place over the' insulator, the insulator y maybe seriously damaged,y wliereasif theaiccan be kept away ffrom the insulator, little or no damage may result other than a momen#V n tary interruption of service to permit the arc inthe air to die out. From tlie'above it will be seen ,ftliatthe increase in rdiameterilue to the cage or conductor guard may be yvery beneiicialin raising the voltage whichk it isy possible `to carry by a `conductor or insulator string'witlioutarcing to ground.

f jln'fthe installation shown yin Fig. `1, a con.

ductor arm 1ly extending transverselyof the line 2 carries an insulator'lQ surrouiidingyits outer end. This construction provides an insulated fluir cont-rol member lto control the field, particularly near the llower rpart oftlie insulator. yAny desired'numbei' ofthese con-` trol members may be used andmay extend in differenty directions from thejsaddle 8. This iuX control 4improves the electrical gradient in the insulator string and lowers the air gradient around the clamp and insulator y iittings. By improving the field.y andlower- *y ing the current inthe streamers'tending` to' discharge or' plume rat the clamp or insulator fittings. the iaslio'ver of the .combinationis' mately 56%fincrease Without increasing the sizeof the insulator -oitlietower clearance. If the insulator stringisused with a larger or more expensive insulated lflux controh the lashovervoltage may be raised fromfapproxi-` mately 350 k; v. tokapproximately .490l .v.y

The voltage cannot be raisedy further by insulated flux controls in the immediate vicinity of the insulatorlstring for an arc will start from the conductor twoV or three eet from thel insulator string and go to the cross-arm or body of the tower or supporting structure. As the lashover obtained With the cage 41 and the smaller insulated control was approximatelyeti'lrv. it will be seen that the conductor screenincreases the tlashover from 490 k.y v.-to 545 k. v. This higher liashover which cannot exceed 490 k. v'. without screen- 'ing or Jcaging the conductor in the vicinity ofthey tower is made. possible by the use of the cage 4t, which in addition improves the stress distribution kinthe insulator' string, and vin some cases may permit the high flasliover without-the use of insulated control orother vcontrol devices to control the gradient inthe -insulator or the ieldJin the vicinity of the insulator.- f n This improving of the stress distribution tends to permitthe operationof the insulator at a higher voltage and also Sets up a stronger fieldr which tends to prevent the formation ol an arcor plume in the vicinity of the insulatorand while an arc is forming tends to repel same, asexplaiiied above. From the above it-'Will be .seen that caging the conductork not only raises'the plum ing point of the conductor in the vicinity of the tower ywhere the field is stronger than out on the line, thus permittinga higher applied voltage without arcingto ground, but in addition the stress distribution of the insulator string is iinproved. Furthermore', the cage maybe so made soas to yprotect the conductor -fromy powerarcs which might seriously damage the same. The use of tbe cage has a further advantage in greatly increasingy ythe iashover under high frequency disturbances where the tower. clearance is small. The use ot the cage will permit a given flashover, particularly under high yfrequency conditions with much smaller tower clearance or in a stronger field thanis possible without guarding the conductoi', thereby permitting considerable saving in the cost of supportingY structures.

The' use of the conductor guard is not necessarily confined to suspension insulators,

but maybe very eiiicient in .improving the dis-` tribution of stressin alstrain or dead-end insulator and in raising the arcing or pluiningv voltagel of the jumper connecting the two dead-end strings on eitherside of the tower.

' The conductor caffe ma" be made ina varietv :D t of'forms, and the size ot' the spiral or cage and its relation to the conductor may bevari'ed so as to develop the maximum tasliover for a given positionot a conductor. 1 the` relative positiony of the cage and 'conductor maybe controlled by the supT ln Fig. n

porting .bar '5 and the clamping members Y' 9.A By malringthe conductor guard of open construction, the concentration of drip water is eliminated and the cost` of the guard kept down. The concentration .of drip water, if permitted, Would tend to form a. conductingpath which would start a plumeand lowerthe flashover, particularly Where the cageor guard has a large projecting surface, which accumulates and concentrates considerable drip Water. Where the conductor guard is made of a solid member, such as a tube of sheet metal, it is advisable to. corrugate or perforate the guard so that the drip Water will not be concentrated. The conductor cageV may be so made that it will not only improve the gradient of the conductor in the vilinit-y ol.i the tower, thereby raising its lashover. but Will improve the stress distribution in the insulator string, and further can be made to protect the conductorI from damage by power arcs, and can be so termed and installed as to eliminate seri-ous discharge from the clamping or other insulator attachments. rl'he use of the conductor` guard permits higher operatingvoltages and frequencies Without arcing rominsulators, conductors andl iittingsfrom a given tower clearance, which Will permit smaller clearance and therebyetfect a. considerable saving. The cage may so improve the stress distribution and l'lashorer values of the combination that the use of the insulators in the string having ditlerent relative electrostatic capacities can be eliminated where a line-distribution 'ot'.v stress is desired. This would permitithe use of one insulator throughout the string with its attended advantages as regares iirst cost and maintenance. there it is desired to raise the voltage after an installat-ionis made it frequently occurs that there isnot suliicicnt clearance to permit an insulator ot suiiicientv size Without reducing the clearance softhat arcine' will occur. 't will be seen thatv the conductor guard is ot particular advantage in a case et this kind as it permits an, increase in the voltage without danger of ar "lng, such as would occur in ordinary construction, due not only to high. pluming voltage of the conductor, but also to the greater eliiciency of the insulator permittingfa shorter insulatorV with greater clearance.

The construction shown in Figs. 2, Baudet is somewhat similar to that shown in F ig. l, except that in this ease a series of brackets or spiders Q3 and 2st are distributed along the conductor Q and carry at their outer lendsa plurality ot bars Q5 Which retain the eoil in fixed position relative to the conductor 2. By controlling the spacing ci" the coil. 26 from the conductor the strength of the lield surrounding the conductor mayl be correspondingly controlled for different positions to best protect it for particular installations.

In the form of the invention shown in Fig. a tubular member 3S is spirally wound around the conductor 2, one end ofthe niember being secured to the supporting saddle aty and the other end being attached to the; cable 2 by a clamp 39. Supporting brackets 4l may be provided at intern'iediate positions as required.

I claim :k y

l. The combination with a high potential transmission line, and a series of Connected loops of conducting material surrounding said line and electrically connected therewith and spaced troni one another to provide an openworl; cage extending longitudinally of said line.

2.y The combination with a transmission line, having a support, ot an openwork cage disposed adjacent said support and extending longitudinally ot' said line, said cage comprising an elongated member ot conducting material wound in a helix about said transmission line.

3. The conibination with a highpotential transmissionv line, having a support, of an openwork cage extending longitudinally of said transmission line adjacent said support, said cage comprising an elongated conductor Wound in a helix about said transmission line, and means for supporting said conductor onsaid line.

et. Thecombination with a high potential transmission line, having a support, ot a flux controlling cage extending along said trailsmission line adjacent said support, said cage comprising an elongated member of conducting material Wound in a helix about said transmission line, and a support intermediate the ends oi' said cager'or holding said cage in spaced relation with said line;

5. The combination with a high potential .transmission line, having a support, et' a sup-` porting rib adjacent said support extending longitudinally oi said line and spaced therefrom, and a helieally wound conductor Supported by said rib and disposed about said transmission line. Y

(5. The combination with a high potential transmission line, et a-pair of spaced brackets mounted on said line, ribs carried by said brackets in spaced relation to said line, and an elongated conductor Wound in a helix aboutsaid ribs and line.

7. The combination with a high potential transmission line, having a support, of spaced brackets mounted on said line adjacent said support, supporting ribsv extending longitudinally ot said line and secured to said brackets, and an elongated member of conducting material wound in a helix upon said ribs.

S. The combination with ahigh potential transmission line, having a support, of'a helix ot' conducting material surrounding said line and having one enddisposed adjal cent said support, the opposite end of said helix being tapered toward said transmission line-and attached thereto.

lll)

y 9.\,Tl1efeo1nbination with a high potential transmission line, having ak support, of

brackets attached to said line, a supporting i rib carried by said brackets and having one 5 `end thereof adjaeentsaid support and the opposite end thereof inclined toward saidline, a member having a rounded outer surface for connecting said inclined endto said line, and

ARTHUR o. AUSTIN. 

